One vertex per element, one color per generator, with an edge from x to x·s.
(2,6)(4,7)(9,10)(11,15)(12,13)(14,16)(25,26,30,31)(27,28,35,32)(29,33,37,39)(34,36,40,38)(1,2)(3,7)(4,8)(5,6)(9,11)(10,14)(12,15)(13,16)(17,18,20,22)(19,21,23,24)(26,31)(28,32)(29,37)(34,40)(2,6)(3,8)(9,11,13,16)(10,15,12,14)(17,18)(19,21)(20,22)(23,24)(25,27,30,35)(26,32,31,28)(29,34,37,40)(33,38,39,36)(1,3,5,8)(2,7,6,4)(9,11)(10,14)(12,15)(13,16)(17,19,20,23)(18,21,22,24)(25,28,30,32)(26,27,31,35)(29,38,37,36)(33,40,39,34)(1,4,5,7)(2,3,6,8)(9,12,13,10)(11,14,16,15)(25,29)(26,33)(27,34)(28,36)(30,37)(31,39)(32,38)(35,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.